1. Field of the Invention
The present invention relates to a power system and, in particular, a power system that includes an internal combustion engine having primary and secondary combustion chambers.
2. Description of the Related Art
As such an internal combustion engine, an arrangement is known in which a lean primary gas mixture is supplied to a primary combustion chamber via a primary intake valve, a rich secondary gas mixture is supplied to a secondary combustion chamber via a secondary intake valve, and the flame generated by combustion of the secondary gas mixture induces ignition and combustion of the primary gas mixture (for example, Japanese Patent Publication No. 61-31301). In this internal combustion engine, excellent combustion efficiency can be obtained by burning the lean primary gas mixture. Furthermore, since the combustion occurs uniformly, it is possible to reduce pollutants such as nitrogen oxides and carbon monoxide.
However, since the conventional arrangement employs, as the secondary gas mixture, a hydrocarbon fuel which has a low combustion rate, it is difficult to further improve the combustion efficiency by fully increasing the leanness of the primary gas mixture.